Tunnel Allocation and Protection in Hierarchical Cross-connect WDM Networks

• Main Authors: Tse-Yu Lo, 羅澤羽
• Other Authors: Chien Chen
• Format: Others
• Language: en_US
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/16785826277593418611

碩士 === 國立交通大學 === 資訊科學系所 === 92 === Multi-granularity Optical Cross-Connect (MG-OXC) has been proposed to provide a cost efficient way to support the increasing number of traffic requests. In the MG-OXC networks, consecutive wavelengths are bundled to form a tunnel and switched as a single unit. Networks resources, including switching fabrics and multiplexers, at the mediate nodes on the route of a tunnel thus can be reduced. This thesis considers the static tunnel allocation problem and the protection problem in MG-OXC networks. For the tunnel allocation problem, a heuristic Capacity-Balanced Static Tunnel Allocation (CB-STA) [1] has been proposed. CB-STA always tries to allocate a tunnel from the node with maximal predicted traffic going out to the node with maximal predicted traffic coming in. However, the length constraint is not considered when selecting node pairs. We propose a heuristic, Constant Length Weighted Tunnel Allocation (CLWTA), to overcome this problem of CB-STA. Only node pairs whose hop distance complies with the length constraint are tried to be allocated tunnels in CLWTA. We examine the performance of the proposed schemes, CLWTA, and make a comparison with CB-STA. The results show that CLWTA outperforms CB-STA in all switching type combinations. For the protection problem, we investigate the protection schemes for the single-link failure in the MG-OXC networks. Since the protection problem has not been studied intensively in MG-OXC networks, this work aims to provide an efficient protection solution. A segment-based protection scheme, called Tunnel-based Segment Protection (TSP) that considers the tunnel allocation with protection requirement in mind is proposed to recover the communications interrupted by a fiber cut. In TSP, a corresponding link-disjoint protection tunnel is always allocated simultaneously with a working tunnel. Simulation results show that TSP provides an efficient protection solution for MG-OXC networks.